Thursday, March 09, 2006

'Atlantic thermohaline circulation' (ATHC) is the technical term for the flow of warm water from the tropical Atlantic up to the north, the system that includes the Gulf Stream.

Despite being on an equal latitude with many freezing bits of Canada and Eastern Europe, we Western Europeans enjoy a much milder climate thanks to the huge warmth brought to us by the ATHC. It currently transports about 1 petawatt (10 to the power of 15 Watts) of heat poleward, a million billion Watts.

To give some proportion here, human civilisation currently uses 10 terawatts of energy (10 to the power of 13 Watts), so the heat transported by the ATHC could run 100 Earth civilizations. Conversely, 1% of the heat transported by the ATHC could supply all of humanity’s current energy use. As a result of this enormous northward heat transport, Europe is up to 8°C warmer than other places on its latitude, with the largest effect in winter.

But if climate change continues, the Greenland ice sheet will melt and flood cold freshwater into the Atlantic. If it does it rapidly enough, it'll shut down the Gulf Stream and we freeze.

It's happened before. The rise in temperature 15,000 years ago caused a North American ice sheet to melt, shutting down the ATHC and returning northern Europe to ice age conditions for 2,000 years.

Enormously scary, yes. But how likely is it really?

Last month, at the behest of the UK Government, the Met Office hosted an international scientific conference on climate change called Avoiding Dangerous Climate Change. The top scientific minds on the subject, all in proper scientific 'just the evidence' mode.

They found that, if we don't slow down our CO2 emissions - taxing the fuck out of producing them being the obvious way to encourage us - there's a two-thirds chance of shutting down the ATHC.

The threat can be

reduced from a 65-in-100 occurrence for no initial tax to a 28-in-100 occurrence for an initial tax of $100/tC[per ton of Carbon emitted]. If the tax were initiated 30 years later in 2035, then the $100/tC tax would reduce the 65-in-100 likelihood to a 42-in-100 likelihood, and a $200/tC tax somewhat further to a 38-in-100 occurrence.

Two-thirds odds on!

And even in the unlikely event of an immediate emissions tax of $100 a ton (about 6p per litre of petrol), there's still a one in four chance of shutting down the ATHC!

To see how likely such a tax would be, it would mean about $1m a week for every transatlantic jumbo jet; would airline lobbyists take that lying down? Now extrapolate your answer to all of the fossil-burning industries.

The report ascertained that the threshold of ATHC shutdown is a rise of 2.3°C. This is similar to the tipping point for other systems as mentioned by other speakers at the conference. 2° is where we see risk of collapse of the Amazon ecosystem, the end of Austrlian tropical forests, and by 2080 nearly half of humanity at risk of water shortage.

Two degrees. Emissions of greenhouse gases are likely to raise global temperatures by between 1.4° and 5.8° during this century.

In the light of all this the authors of the conference report concluded, 'It would therefore seem that the risk of an ATHC collapse is unacceptably large and that measures over and above the policy intervention of a carbon tax should be given serious consideration.'

The report is broken into four pdfs, all available here. Tony Blair's foreword gets one of its own. In it he says, seemingly in contravention of the report's findings and without any explanation of what he means, 'Action now can help avert the worst effects of climate change. With foresight such action can be taken without disturbing our way of life.'

Er, the people who know what they're talking about just said we need measures over and above the carbon tax that would eradicate a serious proportion of international trade, spell the end of mass use of cars and aeroplanes and increase the price of absolutely everything.

Listen Tony, and anyone else who thinks there'll be a hydrogen/biodiesel techno-fix, and anyone who deliberately breeds more Western consumers, and anyone who ever sets foot on an aeroplane; carrying on with our way of life means fucking everything up in the near future.

If we don't 'disturb' our way of life then we are seriously disturbing those who come after us. We get our cheap flights at the expense of them having enough food, heating or medical supplies.

To knowingly overconsume now is to say either, 'I'm going to take someone else's share' or 'I don't give a fuck about the survival of people two or three generations hence, nor a huge proportion of other species'.

A rise in temperature changes how other lifeforms react. They certainly have no alternative technologies to help them. If the acidity of the oceans takes out the plankton, it takes out the rest of the marine foodchain. If it makes plants flower out of synch with the insects that pollinate them, they don't fruit.

It's not just that we depend on the ecosystems we live in for oxygen and food. It is also that we surely have no right sweep away millions of species just to make room for a couple of generations of us having intercontinental travel and strawberries all year round.

Our grandparents did not consume and pollute like us. Our grandchildren will not be able to. Do we climb down from the edge, or do we keep running and hurtle over it?

The gruesome effects are not in some distant unimaginable future. We're talking about ecological collapse and water shortage for half of humanity during the lifetime of children being born today.

If we had lifespans of 500 years, if we had to live with the long-term consequences rather than just the immediate benefits, then we would not be living like this. So how can we possibly justify inflicting it on our children?

5 comments:

For an uncompromising explanation of what carbon rationing would mean for the UK try Mayer Hillman's book "How we can save the planet". Cheesy title it pulls absolutely no punches. It's available from Sustrans at:

She says carbon credits are fair because then people have to pay for what they use. In fact, they are unfair because they let the rich buy as much pollution as they want while the poor go without.

This is even worse when you consider that the rich people and nations use a greater proportion of their resources frivolously. In the same way that we've taken people's ability to feed themselves and replaced it with growing cash crops to supply us with cocoa and cut flowers, so we'll get our long haul holidays at the expense of their essential infrastructure.

She also fails to mention that flying is simply unsustainable. The climate can handle you taking a return flight from the UK to Spain once a year as long as you are responsible for no other emissions; don't flick a light switch, don't get on a bus. Any more than that and you're taking more than your share.

She talks of how the airlines themselves want more energy effiiect models and develop new generations of aircraft. The standard plane for going on very long haul is the 747. It has been in service since 1969.

Why, then, do environmentalists campaign for new airline taxes (which would be totally ineffective) or for outright bans on air travel (which will never happen), instead of arguing calmly for the economically rational solution of bringing airlines into a carbon-trading scheme?

Because econommic rationality is not enough to bring the world to sustainability. In believing we should take the measures that make us sustainable - acting as if it mattered whether the planet can support the people and other species living on it a century or a millennium into the future - I am apparently being 'authoritarian'.

she is partly right that aviation is singled out because airline travel is seen instinctively as a luxury, an indulgence of the prosperous classes. I'd be interested to see anybody try to deny that.

Surely the luxuries are the first thing we should cut back on. Taking a hammer to our only life support machine is more understandable if it delivers things you actually need rather then merely want.

She's effectively arguing that those with money should be allowed all the luxuries they desire, and those who can't afford should cut back on essentials.

But the key point is that for those who fly, aviation is their biggest contribution to climate change. They do it unnecessarily.

Still, I take heart from the fact that such a narrow money=virtue slimeball is aware of people campaigning for an end to aviation. We've got some radical things on the agenda pretty darn swiftly.